Various utility programs, for example some diagnostic utilities, are fully and correctly operable only when all aspects of the computing environment are known and all system resources are available without restriction. For example, a memory diagnostic utility typically tests memory by writing bit patterns to all or a substantial proportion of memory, reading back the written bit patterns and verifying that the bit patterns read are the same as the bit patterns that were written. However, a computer system typically operates under control of an operating system, a master set of programs which controls a computer system and, thus, restricts write access to various locations in memory.
An operating system which is activated by bootstrap loading from a disk drive may be called a native operating system. The file system of the master set of programs making up the native operating system may be called a native file system.
Operating systems, such as Windows.TM. and OS/2.TM., provide a known environment and make system resources available by establishing a virtual environment for running utilities. The virtual environment invoked is typically called a DOS box. Unfortunately, DOS boxes are a virtual environment and do not furnish a control environment for the physical computing environment. Rather than furnishing access to the entire physical system, an operating system often interprets or ignores various instructions that are executed by the utility.
One example of a limitation of DOS boxes arises in the Windows NT.TM. operating system. Windows.TM. traps input and output (I/O) operations. The Windows.TM. operating system also is known to restrict the I/O operations of utility programs.
Conventional methods for performing utility functions without interference from the operating system include bootstrap loading a special operating system that is established for the purpose of running utility functions. In other systems the operating system is established in conjunction with utility programs so that a utility is allowed access to particular system resources. A computer system manufacturer can address also some of these problems by creating a separate partition on the disk drive, loading the utilities onto the separate partition and encrypting the utility programs so that the utility programs cannot be executed by a casual user.
Another conventional technique for establishing a utility operating environment which avoids these restrictions involves creating a separate bootable partition on a disk drive and subdividing the disk drive storage area into smaller units allocated to specific tasks, including the utility operating environment tasks. However, this technique requires inflexible and constant reservation of portions of a user's physical disk drive.
Several problems arise from this unrelenting reservation of storage resources. First, if a computer user repartitions and reformats the storage system without properly re-establishing the utility environment, the utility programs cannot be reinstalled without unloading all data on the storage system and appropriately reestablishing the proper partitioning.
A second problem arises if a computer system user accidentally or inadvertently deletes the program files which make up the utilities. Files which make up the utility partition are typically large files with names that are obscure to the computer user. A computer user running low on storage resources may delete the large, space-consuming, obscurely-named utility files without understanding their importance. Restoring deleted utility files is difficult and expensive because the files often include multiple megabytes of information which must be written onto a transfer media such as multiple floppy disks. The transfer media and the time needed to write appropriate files to the media are expensive for a manufacturer providing the programmed media and for the computer user. Furthermore, the utility files are typically restored by transferring information on multiple floppy disks, perhaps a dozen disks, to a hard disk drive, a very time consuming task to the computer user.
A third problem is that the computer user cannot easily make use of the disk drive space used for the utility environment in an emergency situation.
What is needed is a technique for furnishing a known operating environment in which all resources of a computer system are fully accessible and the storage resources for implementing the operating environment can be removed and reinstalled easily upon user command.